The electrospinogram was investigated in 18 adult rabbits before and after acute spinal lesions of variable entity. The first positive wave is widely distributed from L7 to Th11-12 and seems to be generated by a dipole placed within the cauda. The following 'M'-shaped complex is propagated up to the cervical segments probably along the primary afferent pathways in the dorsal columns ipsilateral to the stimulated side. Local reflexes of mono- and polysynaptic loops are also present. Standardized seriate clinical observations did not provide reliable data on level and extension of the lesion until 16-24 h, while the electrospinogram showed a 'killed end' potential already within the first 60 min. Furthermore, this noninvasive test furnishes early tools about the width of the anatomical damage.